worldgen of a custom block

hello,
We are a very small community server with just 2 hands of player, originally we came all from an other server and decide to stay together as the former server closed. There the server had as a theme "Dinosaurs" as we liked that theme i was thinking of using a datapack to implement some cool stuff. This server is not a pay to win server, i pay everything from my own pocket to keep our small community alive.
i am completely new in the topic datapack or creating datapacks. i have an idea in mind which in my eyes is perfectly fitting to a datapack. i will try to roughly describe it and also what is already in place.
basic idea: