Was Milky Way formed after Sagittarius A Explosion? Is it possible that most galaxies (and our galaxy) were formed from leftovers of supernova explosions?

In order to have a black hole 4,000,000 x solar mass the initial mass of the star should have been even greater. 

So I was thinking, is it possible that after the big bang, gas formed much bigger stars 1,000,000,000,000,000,000,000x bigger than the sun, which later exploded forming: 


black holes in the middle of future galaxies
Gas, which later created smaller stars, planets, etc.


Am I trying to reinvent a bicycle here?
This is ruled out because that's not what we see when we look back in the past. 

If this was the case at the beginning, we would see these huge stars, with probably different characteristics from the ones formed only recently. But we don't see anything like that. 

From what we see when we look very far away - that's few hundreds of millions of years after the beginning - we see signatures of first generation stars forming, very big stars indeed, but nothing close to what you're talking about.