### Detailed Worldbuilding with Spider-like Centaur Aliens

**1. Alien Physiology and Society:**

- **Appearance:** The aliens, called the **Arachni**, have the upper body of a humanoid and the lower body of a spider. They possess multiple eyes, mandibles, and limbs capable of producing silk.

- **Hive Families:** Arachni live in small hive families, led by a matriarch or queen. These hive families are deeply connected and work together in all aspects of life, from construction to defense.

**2. Alien Culture:**

- **Beliefs and Practices:** The Arachni religion centers on the **Web of Life**, a belief in the interconnectedness of all things. Their rituals involve weaving intricate web patterns that symbolize different aspects of their world and universe.

- **Sacred Sites:** Sacred sites include large communal web structures used for ceremonies and important gatherings. These webs are woven with extraordinary skill and are considered sacred.

**3. Planetary Ecosystem:**

- **Habitats:** The Arachni live in areas rich with tall trees and natural structures where they can anchor their webs. Their settlements are built into and around these environments, blending natural and web-made structures.

- **Flora and Fauna:** Unique flora and fauna abound, including giant, web-building plants and symbiotic creatures that live in harmony with the Arachni. Some plants and animals are sacred or hold significant cultural value.

### Plot and Conflict with Religious and Social Dynamics

**4. Initial Tensions:**

- **Territorial Disputes:** The human settlement might unintentionally encroach on Arachni sacred sites or web structures, causing immediate tension.

- **Cultural Misunderstandings:** Early human actions, such as cutting down trees or harvesting materials, might be seen as disrespectful or sacrilegious.

**5. Escalating Conflicts:**

- **Religious Zealots:** Some Arachni may see humans as a threat to their way of life and religious beliefs, leading to skirmishes or attempts to drive them away.

- **Internal Strife:** Within the human community, disagreements over how to handle interactions with the Arachni could lead to internal conflicts.

**6. Diplomatic and Religious Intrigues:**

- **Negotiations:** Human leaders and Arachni matriarchs might engage in delicate negotiations, balancing human needs with respect for Arachni customs and religious beliefs.

- **Religious Syncretism:** Attempts to find common ground could lead to new hybrid practices, fostering a unique cultural exchange.

### Characters and Factions with Complex Interactions

**7. Diverse Characters:**

- **Human Leaders:** Include a range of human characters, from pragmatic leaders to idealistic diplomats, and everyday refugees with varied views on religion and coexistence.

- **Arachni Leaders:** Key Arachni characters could include a wise matriarch, a fervent religious leader, and a diplomat curious about humans.

**8. Factions:**

- **Human Factions:** Develop human factions such as secularists, former theocrats, and pragmatists advocating for different approaches to dealing with the Arachni.

- **Arachni Factions:** Introduce Arachni factions, including conservative hive families, reformists open to new ideas, and radicals who oppose human presence.

### Technology and Resources with Religious Contexts

**9. Alien and Human Technology:**

- **Arachni Technology:** Arachni use webbing combined with wood, bone, and natural fibers for construction and art. This results in structures that are both functional and beautiful, with web patterns often carrying religious significance.

- **Human Technology:** Human technology, particularly metal and machinery, might be viewed with suspicion or awe by the Arachni, potentially leading to conflict or trade opportunities.

**10. Resources:**

- **Resource Scarcity:** Competition for resources like wood, water, and food could drive conflict, especially if these resources hold religious significance for the Arachni.

- **Unique Resources:** Introduce unique resources, such as the exceptionally strong Arachni silk, which could be valuable for human use in construction, clothing, or technology.

### Story Hooks with Religious and Social Dimensions

**11. Story Hooks:**

- **Prophecies and Omens:** Arachni prophecies or omens regarding humans could add a mystical element to the plot, influencing how different Arachni factions view the human settlers.

- **Religious Relics:** Discovery of powerful or sacred relics, like ancient web artifacts or significant bones, could become central to the plot, with both humans and Arachni vying for control.

- **Moral and Ethical Dilemmas:** Present dilemmas such as whether to respect alien religious laws that conflict with human survival needs or moral principles, forcing players to make difficult choices.

### Practical Tips for Integrating Religious and Social Themes

**12. Realism and Sensitivity:**

- **Respect and Sensitivity:** Handle religious themes with care and respect, ensuring they add depth without alienating players.

- **Depth and Complexity:** Portray both positive and negative aspects of religion and culture, showing variability and depth in belief systems.

**13. Player Involvement:**

- **Character Arcs:** Encourage players to develop their characters’ relationships with religion, alien cultures, and each other.

- **Choice and Consequence:** Ensure player choices regarding religious and social interactions have significant and meaningful consequences in the game world.

By incorporating these detailed elements, you can create a rich, immersive, and complex campaign setting. This will allow for deep exploration of themes like religion, culture, survival, and coexistence, providing an engaging and thought-provoking experience for your players.