Kino probbly was just a baby left on Mystic mt. by neglectful parents. Finding a baby crying his brains out all alone might have mystified tha cave peeple becuz,well, they're cave peeple. Oooooo magic baby, have no parents, come from magic, mystic land from tha sky.This mystic place where we find magic baby.This Mystic Mt.!!! He WAS important 2 the timeline, being Marles ancestor and all, but not enough to cause a time warp. And if Leah really is Aylas mother sent thru time to 1020 AD.,then she would be more important 2 the timeline than Kino, yet she didn't show up till AFTER crono and co. changed history. All in all, I think that gate was created so crono and co. could witness Lavos's fall, and possibly 4 Marle to come in contact with her distant Ancestor, just so everything in CT could come 2gether more smoothly at tha end.
Sorry 4 such a long post