Programming

I highly recommend, for a first project, to limit yourself to just one game mechanic.

Limit your scope

For example: It sounds like you want to make a platformer? Maybe limit yourself to just an endless runner type where the character has to jump over obstacles. A bit like flappy bird but your character is grounded instead of flying. This way, you can focus your effort on at least two major aspects of the game:

• Character movement
• Map generation

Game Design Document

Another thing to consider doing is putting together a game design document. Write down what kind of game you want to make, and break it down into their constituent mechanics. Then, maybe try ranking them from what you think could be the easiest to implement to the hardest. You may want to look up tutorials on how to implement those various mechanics and rank them that way if you're unsure.

Having a game design document can be helpful, especially if you remind yourself not to go beyond the scope you have set out for yourself. It may help you focus on what you need to do and not get distracted by new features you just thought up of. Not to say you should throw those new ideas out, but write them down under "future ideas" and worry about them after you have a minimum viable product.

To be fair, not everyone will agree on how helpful this can be, but I think having something written down can help act as a reminder, or a means of focusing yourself. Wouldn't hurt to try

Bugs

As for bugs, honestly, that's part and parcel of programming. One thing that I found works for me when I get too frustrated is to step away from the computer. Take a snack break, or go for a walk, or play a game. Come back with a clear head, and I usually figure out my issue.

I hope that helps provide some guidance on overcoming that overwhelming feeling. Best of luck to you!

/u/Mifuyne said it better than I can. "Big Ideas" almost never work for a first-time game. It's usually safe to assume, most big published games have taken teams of people multiple years to build. I have some experience, but big ideas are still always my downfall.

Your first game should be a learning experience, and you should aim to finish as fast as possible, while still doing good work. If you are set on a platformer, try an auto-runner like the other comment suggests, or look at arcade games. One level from Donkey Kong or Mario Bros (not Super Mario Bros) is about the limit of complexity I'd suggest for a new dev. Even NES games like Super Mario Bros are pretty complicated, and would take a new developer many months. And there's no shame in copying a classic game's mechanics for your first game.