Manning and Brees do not make my top 5 QBs all time let alone top 5 NFL players all time.
Everyone has their method but I believe you can’t compare well across eras so you pick the best if each era to start then do your best to sort between them.
40s-50s - Graham
60s - Start
70s - Staubach
80s - Montana
90s - Favre
00s-10s - Brady
My ranking:
1. Brady
2. Montana
3. Staubach
4. Graham
5. Starr
6. Favre
So naturally Manning and Brees would sit outside that, let alone Rodgers. Why would being the 2nd or 3rd best QB in an era be better than any of these others who dominated the position at their time. This adjusts for rules changes and evolution of the game.
Let me put it another way. Who was the 2nd best QB during 40s-50s? Oh wait, noone cares. Who was 2nd best QB during 60s? Noone cares. 70s? Some might start mentioning Unitas’ sterling career but memories are fading. 80s? Now it’s getting more recent and people will mention Marino but noone is saying Marino as top 5 alltime like they did then. 90s? More recent and you’ll see mention of Elway or Young but not really.
Similarly now with Manning and Brees. We’ve got recency bias. Manning’s memory will become like Marino or Unitas and eventually fade from that as well. Decades from now people will only remember that Tom dominated this era and they will only compare him to those who dominated other eras, like maybe Mahomes during 20s etc.