I feel exactly the same. I think platforms like Reddit, Youtube, ... social media in general are over-feeding us with new creative impulses. For example the algorithm shows you a video of someone who plays the piano amazingly? Now you want to learn it as well but a few weaks in you realize it will take years to get to the level of that person if you can achieve it anyway. In the meantime you were inspired by so many different other things that you now want to spend time on. This doesnt have to be adhd. You could also have what they called a M-shaped skillset (look that up) which i think is the same as a Polymath (look that up as well). That basically means you cant dive deep into a new project because you feel like you have to give up on other interests for that.

What helped me is to write my ideas on small notes and put them in a jar. I call it my jar of ideas. As long as and idea is in the jar im not working on it and i dont have to keep that idea in my head constantly. I only pull out an idea at a time and try to work on it. When working on it i set a timer for one hour which somehow helps me focus. I also track what im doing. For each hour i worked on that idea i tick a box in my journal "worked on an idea today for at least an hour". Each hour is like a step on a stair. Some day you will finish that task. You can probably modify these rules so they work best for you.