This is analysis paralysis. It's not a mental deficiency, but rather an anti-pattern usually brought on by insecurity and lack of knowledge about which decisions are actually important:
The way out of it is just to pick something and see how far it takes you, accepting that you may have to backtrack and redo stuff in the future. There's this myth that experts got that way through good decisions; no, usually experts got that way because they made a lot of bad decisions really quickly and dealt with the consequences, and so now they know not to make them again.
https://en.wikipedia.org/wiki/Analysis_paralysis
The way out of it is just to pick something and see how far it takes you, accepting that you may have to backtrack and redo stuff in the future. There's this myth that experts got that way through good decisions; no, usually experts got that way because they made a lot of bad decisions really quickly and dealt with the consequences, and so now they know not to make them again.