There are no files or libraries at net.minecraft.client.render that are imported into the mod code.

Why don't I have these files in the archive of minecraft itself? in many mods, this library/file is imported. But I go into the files of the game itself (in the archive), and there is nothing at net.minecraft.client.render, or rather there is no render folder in the client folder (there is only one folder at all!). And so there are not some necessary objects needed to import into the code. Tell me why, they should be there and a lot of references to them. I can't find a solution on the Internet. There should also be models of minecraft creatures there, but there are no files! Minecraft itself works great and mods too. I have slightly adjusted the file from the mod for myself, but now I cannot compile the java file back, since the path in the import does not work, there are no files!