Brother Javaid, you are right about humans being created on earth. Verses 20:53-55 support this. About whether Allah intervened, the following verses may help.
15:28 Recall when your Sustainer said to the angels, “Indeed, I am about to create man out of sounding inorganic matter, (and then) out of hydrated clay.”
15:29 And when I have perfected him in due proportion and breathed into him of My Energy, bow before him.” [Of My Energy = Free will. 76:3]
15:30 Thereupon the angels bowed, all of them together. [The physical Laws in the Universe were made subservient to mankind]
This is telling us: The same Force that created angles(laws of nature) then created humans. and
Laws, that were already there, were made to help humans/be useful once humans were in perfect or best form to use them.
I think Allah, that Great Force, does not have to intervene as He was and still is every where and encompasses all.