Hello! Thank you for trying out our game!
Eve's house should be buildable right after completing the tutorial and starting a new quest. As for other villagers, their houses unlocks after reaching the first level of relations with them. For now, relationship points can only be earned by talking with characters. It will be enough for you to talk with the character 3 times after meeting to get the opportunity to build a house (if the villager says that he is busy or tired, then you've reached communication limit for that day and you need to wait for the next one, but 2 days is enough to level up).
Sorry if it's not quite obvious yet. In future versions, we'll work on interactions with characters so that they are more clear.