Well, sure, copying and inspiration are not the same, but what is the line that defines what is a copy, and what is an inspired original? You could say they're subjective, but there are objective things we can assess. Ripple Dot Zero and Freedom Planet are good examples of inspiration. They start with the feel and aesthetic of something, and create originality from that. An imitation is when something just flat out copies bits and pieces of something else and tries to pass it off as its own thing. There can be grey areas where opinion is a factor, and that's fine, it's human to agree to disagree.
In an objective point of view, however, that's not the case. You can't say that a dissonant harmony is correct in theory because it's just your opinion - there's a theory and doctrine to work off of, and to break that... is, unfortunately, professionally wrong.
That's the point I'm getting at, here - there's gotta be an objective viewpoint, or there's a chance the aforementioned inspired originals would not have passed the radars. (Also, copyright law would be haywire.) I can't say for myself that I know where this objective line is... But what I can say, however, is that when compared to the likes of Freedom Planet or even After the Sequel, this game's certainly a more risky affair. To compare with the latter, being a fellow fangame, AtS starts with basics from the source and creates a bunch of original art and ideas - Reborn, however is copying bits from AtS, or imitating large pieces of it, backing it up with substantially less original ideas.
I'm not trying to condemn this fangame for having inspiration from/copying the After/Before the Sequel duology - I'm trying to recommend adding your own touch of creativity into the inspired mix to make said inspired product yours, and truly yours.
As LakeFeperd has said, the auto-scrolling boss battles were inspired by Sonic Advance 2 - inspiration from a basic concept. I'm not saying anything against that; it's fine, fun and perfectly normal!
And that's because he, taking concepts into account, added his own creativity in the form of original bosses, effectively making a new and original twist on an existing concept. It's inspired, but inherently original.
But, being a Sonic fangame, he worked from the source. It's not the same as taking Lake's inspired idea and then twisting that into your game, so to speak.
That's all I'm saying about this - Inspiration is perfectly fine. I wouldn't be anywhere without it, in my own career as a musician. What I'm saying, however, is that you need to work from your own creativity and ideas instead of directly copying, and make it truly yours.
I'm not sure about you, but I don't particularly feel like playing what is basically a mishmash of ideas taken straight from sources, after all.
Again, I'm not trying to discourage you, DarkchaoX10. The short answer is that inspiration is fine, and is perfectly normal - but it's also recommended at the same time that you put your own creativity into the mix so that it becomes yours, and inherently yours.