I have seen the movie multiple times, by the time of this post. You say "other than Ultron helping to create him", but that is the vision's origin. Ultron creates him, though instead of wonder man or maybe the original human torch being added, they used JARVIS. This does not compare to Warlock's origin, or HIM as he was called back then. He was made as the ultimate human creation, by humans. The vision's body was made by ultron. Also when HIM fought Thor, Thor pummeled him and Warlock cocooned himself and fled into space. The vision didn't really fight thor.
Also your defining motif of the gem on the forehead is not exclusive to Adam Warlock. Check out the infinity quest. The Champion, The Gardener, and The Runner, all wore a gem on their forehead. The In-Betweener also wore his gem on his forehead, but he had the soul gem after Warlock, so I didn't count him since that example is similar to Warlock. The Vision doing it just seemed like a perfect fit. All that happened was the Mind gem replaced his solar jewel.
And like I said before Warlock had the soul gem, vision has the mind gem. Adam Warlock is not born with an infinity stone, the high evolutionary gave him the soul gem. The Vision in the movie is born with the mind gem. So the Vision having the mind gem doesn't seem tied at all to Adam Warlock's origin.