If Cell had killed Gohan...

[Super Vegetto]

Lol that picture is so wrong xD

[KentalSSJ6]

Those look nothing like Funimation's subs. Your source for that screenshot?

[Godo]

That just mean's Gohan's Saiyan DNA is superior to his human part when it comes to ki sense, hence why Piccolo senses Goku's ki without mentioning Chichi?

You are comprised by a mix of the DNA from your mother and father. This doesn't make you either your father or your mother. You are you.
Even though your appearance may be more like your father's, you are still you and are still comprised by the (equal) mix of genes from your parents.

You are confusing an offspring with a clone.
A clone consists 100% of one organism's DNA.

If Goku is cloned into another Goku (with 100% of Goku's DNA), then the clone is also Goku. Not in identity, mind you, but in phenotype and genotype. You could go into this deeply philosophically, but let's not do that.

What Cell is, is essentially an organism made up of a mix of cells from Goku, Vegeta , Freeza and King Cold, as well as other organisms. He could be seen as an artificial offspring of these lifeforms, though not as Goku, Vegeta, Freeza as individuals.
What they sense when Cell powers up is simply a mix of the ki from all these organisms (which is logical). This is clear during the scene in the manga.