I'd say there's a connection between Supes and Manhattan, but I would NOT say they are one and the same. That would require ignoring pretty much all of Rebirth to this point. And most of DC's history as well.
"Oh, yeah. Forgot to tell ya, Lois, I'm actually a God-like being from a universe where I was basically the only super-powered person ever. With the power to completely warp reality!"
"Oh, Bruce! Yeah, did I tell you how I'm actually a blue human with powers beyond the Fifth Dimensional Imps? That, at any point in time, I probably could have brought your parents back to life with no negative side-effects? Still besties, right?"
"Barry! You know Flashpoint? Turns out, wasn't your fault after all! I just couldn't help but screw with the hole you ripped in the space-time continuum when you tried to undo Flashpoint. Why, you ask? Oh, just a whim."
Should I go on?