This post compares the lizard man/lizardfolk entries in AD&D/D&D across editions from 1e to 5e. It finds a correlation between shamans/witch doctors and evil actions, in particular eating sentient beings. Likewise there is a correlation between druids/mystics and a lower incidence of 'cannibalism'.
1e MM: "[L]izard men are likely to prefer human flesh to other foods. In this regard they have been known to ambush humans, gather up the corpses and survivors as captives, and take the lot back to their lair for a rude and horrid feast."
As per the 1e DMG rules for tribal casters, lizard men have shamans and witch doctors. Intelligence is "[l]ow (average)". My interpretation of this is that the 10% of lizard men that "evolved to a higher state" have average intelligence (8-10) while the remaining 90% are of low intelligence (5-7).
2e lizard men are very similar to those in 1e - the quoted text above is repeated in the Monstrous Manual. They have shamans but not witch doctors, the latter having been almost entirely removed from 2e. War leaders and potentially lizard kings are their leaders.
3e MM: "[P]opular lore holds that lizardfolk prefer humanoid flesh, but this charge is largely unfounded (though some tribes do eat captives or slain foes)... Shamans offer advice but rarely become leaders themselves… Most lizardfolk leaders are barbarians or druids. Lizardfolk clerics (shamans) worship Semuanya."
Druid is their favoured class. They have intelligence 9, due to an intelligence penalty of -2.
4e MM: "Some especially cruel and savage lizardfolk capture and eat other humanoid creatures, boldly launching raids against the lands of nearby humanoids to capture victims for their feasts... Shamans and mystics commonly advise the chieftain."
The lizardfolk controller is a "Greenscale Marsh Mystic". Intelligence scores range from 5 to 10, with 8 being most common.
5e MM:
Lizard folk… have a taste for humanoid flesh. Prisoners are often taken back to their camps to become the centerpieces of great feasts and rites involving dancing, storytelling, and ritual combat. Victims are either cooked and eaten by the tribe, or are sacrificed to Semuanya, the lizardfolk god... Lizardfolk shamans lead their tribes, overseeing rites and ceremonies performed to honor Semuanya.
They have intelligence 7.
The only lizardfolk to engage in the sacrifice of sentient beings (5e) are also the only ones to be explicitly led by shamans. That sacrifice is part of shamanic religious practice. The lizard men and lizardfolk that are always 'cannabilistic' (1e, 2e, 5e) have shamans and, in 1e, witch doctors as their sole magico-religious specialists. Both of these have non-European associations. Lizardfolk that have druids and mystics (3e, 4e) are seldom 'cannibals' - "some tribes", "especially cruel and savage lizardfolk". "Mystic" has no geographical associations, while "druid" is associated with Europe. The 3e and 4e lizardfolk are also the most intelligent.
Supplemental note on lizardfolk religious sacrifices:
The idea of lizardfolk shamans performing humanoid sacrifice seems to derive from the 2e Monster Mythology (1992). In this book, the sacrifices are in honour of the demon, Sess’innek, who is worshipped by a small number of evil lizard men. "[Sess’innek’s avatar] is invoked by a shamanic servant in a carefully staged ceremony at which he receives homage and sacrifice." In the 5e MM this appears to have been transferred to Semuanya, a god worshipped by most lizardfolk.