Can I still publish a paper on peer reviewed journals several years after publishing it on ArXiv?
You speak of ideas, yet ideas are worth close to nothing without results, at least in the academic understanding. Sure, they are the beginning, but are not intellectually protected by themselves. Anyone can have an idea, but it takes work to develop that idea into a solid contribution to science.

So, if you have real "discoveries" and "important advances", you shouldn't be afraid to submit them for peer-review, as that is the only way to scientifically validate your work. Otherwise, it doesn't matter if someone develops on your idea and doesn't cite you. Similarly, it doesn't matter where you put those ideas, it could be arxiv, your personal website, facebook, etc.

As stated in the comments, you can submit a preprint and also submit to a journal, the preprint puts a timestamp onto your work so you have time to publish it (even if it gets rejected and you retry). However, this holds only for work that has the chance to get accepted for publication, i.e. has some real contribution.