@RichSabre
I always thought of the Giants as a more primal or beast like species that fall in with all the various animals in middle earth. They may not necessarily have a
fëa
(soul) or at least not one that goes anywhere and simply dies with their
hröa. Therefore they aren't all that important in the grand scheme of things and are just another creature, albiet a very humanoid one and probably one far cleverer than simple animals and most probably with sentience of some sort. Perhaps they are some sort of original experiment or project by Eru before he created his children, maybe he was just experimenting with appearance, size and nature and made the Giants but without
fëa. He may have then left them in this primal state and decided that elves and men should be far smaller in stature but of a similar form. As far as Sauron using them perhaps they were too high in the mountains and too volatile for it to be worthwhile
. I'm sure he could have brought them under his control if he tried hard enough/used enough forces to do so but the Giants may have taken out many orcs in the process so it might have just not been worth it especially when he already had armored Olog-Hai. Just my two cents
As far as the origin of the Orcs I'm not sure why their longevity was one of Tolkiens main concerns if they were indeed created from Tortured/Corrupted Elves as the loss of immortality could easily be explained as a side effect of being so cruelly and fully misshapen and tortured. Morgoth was able to infuse middle earth ITSELF and its various elements (gold, silver, water etc etc etc) with his own essence meaning that every being and place had the potential for corruption or greed. He is almost like corruption incarnate really so I can see him infusing the tortured and twisted elves with parts of his own being and essence which would surely effect and remove their gift of immortality and seems to have also been so full on that they were considered from that point on a different species.
Merely disfiguring and torturing the elves into looking like the orcs do and breaking them mentally would not result in their offspring being the same either so obviously Morgoths essense or will being infused into them must have been what twisted them into a new race. So he hasn't created life but has rather corrupted an existing group of beings into a new type of being.
Edited by PsychoRocka