The same could be said about the illegal murder of your hypothetical child, could it not? You can just grow a new one, no big deal.
The cutting down of a forest is obviously not morally or legally or technically comparable to the killing of a child. I honestly wonder whether you think you are persuading anyone when you make such a comparison, do you really believe that these trees should be held in the same regard as children?
The point is that the damage is not so simple to reverse. There are consequences to destroying and regrowing that would not be felt if the destruction had not occurred.
And the point the previous commenter was making is that the damage is pretty simple to reverse because trees are fungible, a point that is not countered in any way by an incredible analogy to notoriously non-fungible children.
Trees, forests, and the things that live in them are also non-fungible. This was also indicated in my previous comment. Hope this helps!