hey man,
i feel the exact same as you and used to overthink all the time. programming is not easy whatsoever. at the moment i’m in the middle of making my first game. there’s countless things i still don’t know for example structuring big systems but that’s not going to stop me. 
here are my best tips that changed my mentality completely:
1. improve every day: 
time moves quickly as you might know. you must keep pushing for progress every single day.
for example, i learnt type checking and export type today, modeled ropes in blender, planned systems and learnt texture painting.. learning is earning

2. DO NOT STAY STAGNANT: 
if you continue making the same code every day like making a part then you won’t get anywhere! others may disagree on this way of learning but i’ve learnt the most of my scripting knowledge from making my game so far.
3. break everything down into steps: 
you’re thinking too far ahead when you say “i want to make a game”. think like this, it’s 1, 2, 3, 4. not 1, 100. 
if i’m making a car simulator game i’m not thinking “let’s script a car”. i’m thinking “how do i detect if the player is pressing E”? after that is done then i’m thinking “now let’s make a car door opening animation and play it”, etc.
when you break things down into steps, you then realize that it’s easier to progress and when you see progress, you won’t stop. 
games aren’t made in an hour or a day, that’s the REALITY. it takes some studios 1-9 months to complete a game with developers working 6-8+ hours a day.
you must be willing to commit, step by step. developers are no different from you and me, they just kept learning and improving every day. that is why they are so good because they’re always constantly improving! 
just look at how i’m planning one of my systems at the moment. i’ve never made a big system before but i’m breaking this down step by step. i’m taking actionable steps that will move me closer to my goal:
4. always ask for help! 
use the devforum if you ever need any help. there’s no such thing as asking too many questions. i put up forum posts all the time if i need help. you’re doing the right thing by asking for help. your post could help someone else as well. 
ask as many questions as possible. the more questions you ask, the better your understanding becomes, the better you become at scripting. 
there are plenty of developers on discord as well who are willing to help one another. don’t neglect discord servers. google is great for learning resources as well like for math, syntax, API reference, etc.
don't be overwhelmed by the amount of things you have to learn. just learn what you need to learn for your current task.
hopefully that helps you get over your mental block! 