I have a pretty solid belief that any special forces operative (black ops, green berets, ect.) are probably pretty high level and they'll also probably highly trained in magic as a way to enhance their physical prowess.
I'll have to disagree with that. I recall someone once posted a working character sheet of Einstein. Between the various feats and bonuses that he could get, he makes a DC 40 Knowledge (physics) check by taking 20 at Level 5. As a DC 40 is border nigh-impossible, it could be inferred that no real person could be higher than Level 5. Even special ops.
Einstein
+4 Int
+8 Ranks
+2 Masterwork Item (laboratory)
+4 Aid Another (two lab assistants)
+3 Skill Focus
+21 Knowledge (physics) Bonus
This is a flawed connection so let us address the underlying point attempting to be made in your comparison. So, your thesis if we will, is that Einstein could be built under level five and still achieve his amazing breakthroughs within physics and because of this a special operations operative could not be higher than level five as well. If so let us perhaps attempt to analyze what each bring to the table. Einstein was a genius and powerhouse in the field of mathematics, physics and such. So off the bat he's a pretty easy guy to understand in D&D, you just need a dude who's good at hitting a very specialized knowledge check. On the other side of the fence we have a special forces operative who's duties include being able to realistically survive anywhere, kill anyone and never be seen. I mean I could go on for a while on how elite these guys have to be but perhaps we should just look at what is required of the green berets to even start training.
First of all you need to score a General Technical score of 107 or higher and a combat operation score of 98 on the Armed Services Vocational Aptitude Battery. This roughly means you have to be as well as or better than 107% of the nationally representative sample at technical aspects and be as well or better than 98% of the nationally representative sample at killing. So not only do you have to be very good at murdering human beings but you also have be very smart in a wide range of fields (mathematics, science and technology to name a few). So we can make the statement that these special forces operatives are pretty top-notch in attributes & skills.
But we are still brought back to your claim that because Einstein could make a really hard knowledge check, no one (not even special forces operative who collectively do more than Einstein ever would in D&D) could ever get higher than him level wise. And I can, with much difficulty, see where you might be coming from but you seem to be placing a limit on humankind through the barrier of intellectual achievements while diminishing any achievements that would actually level you up in any conventional game of D&D.
Perhaps we should look at your Einstein example and see if we can't polish it up. After all if Einstein is the glass ceiling for any human in D&D, we might as well see if we can't really optimize him.
Albert Einstein: Old Human Male Human Paragon 1; CR 1; Medium Humanoid (human); HD 1d8-1; hp 7; Init -2; Spd 30 ft.; AC 8, touch 8, flat-footed 8; Base Atk +0; Grp -2; Atk -2 melee (1d6-2/x2; club); SA; SQ Adaptive Learning (Knowledge: Architecture & Engineering); AL NG; SV Fort -1, Ref -2, Will +3; Str 6, Dex 6, Con 8, Int 20, Wis 12, Cha 12.
Skills and Feats: Diplomacy +5 (4 ranks +1 cha), Craft (Writing) +9 (4 ranks +5 int), Disable Device +9 (4 ranks +5 int), Knowledge (Arcana) +6 (2 ranks +5 int -2 specialized +1 absent minded), Knowledge (Architecture & Engineering) +24 (4 ranks +5 int +1 specialized +1 absent minded +3 skill focus +4 call to mind +2 masterwork tool +4 aid another), Knowledge (Geography) +6 (2 ranks +5 int -2 specialized +1 absent minded), Knowledge (History) +6 (2 ranks +5 int -2 specialized +1 absent minded), Knowledge (Religion) +6 (2 ranks +5 int -2 specialized +1 absent minded), Perform (Oratory) +5 (4 ranks +1 cha), Profession (Professor) +5 (4 ranks +1 wis), Use Magical Device +5 (4 ranks +1 cha), Use Psionic Device +5 (4 ranks +1 cha); Skill Focus (Knowledge: Architecture & Engineering) and Hidden Talent (Call to Mind)
Traits: Absent Minded & Specialized (Knowledge: Architecture & Engineering)
Sources