So I think what sort of game works for somebody is greatly dependent on the person. As far as new players go I do not think we can meaningfully make a determination what their appetite for complexity is. Someone coming from a board gaming background or who plays Magic could feel at home in a game like Pathfinder 2.
Pathfinder 2 is remarkably clear, concise, and consistent. Things that do similar things work in exactly the same way. Proficiency works the same for skills, saves, armor, attacks, and Perception. Checks are always against a DC with one of four results.
There are not nearly as many special exceptions to the way things work. Instead of granting Wisdom modifier to Armor Class the monk just starts out Expert in Unarmored Defense. The monk's powerful fist ability only upgrades damage to a d6. It does not meaningfully change the way unarmed strikes work. The action economy feels far more fluid and intuitive to me than move, action, and bonus action with split moves and some things costing a portion of your move.
Almost everything is an active ability and comes from one of three resource pools : the action economy, focus points, and spell slots. There are no class abilities with their own individual resource pools or daily uses. There are very few always on passive abilities. I also think it's helpful that Champions (Paladins) and Rangers are not spell casters. Monks who opt in and all Champions do utilize focus spells, but those are far easier to manage.
More than anything else the clear formatting and templates is an immense help to me. Sometimes reading class abilities in 5e during the game was difficult because you have to parse out things like action cost, resource cost, target and effect. It was actively frustrating to me. I just do not get what the issue with clear formatting and using concise English is.
All that being said I do not think Pathfinder 2 is a good fit for someone who does not want to meaningfully interface with the rules of the game. They certainly will not get much enjoyment from what the game has to offer. I think you can guide a new player to slowly learn the game, but if their interests do not align with wanting to get better at the game and improve their skills I would suggest playing some other game with them.
Not really because of character complexity though. The monsters in this game are rough. They invoke nasty status effects that can sometimes last days and have numerous resistance, weaknesses, and immunities. Some like the hydra have specific ways they need to be killed. The classes we normally recommend to more casual players like Fighters and Barbarians are often taking the brunt of things like a Djinni's one a round ability to blast everyone around it back 20 feet with an aura that makes it so the space around them is difficult terrain or how a Gibbering Mouther can attack as a reaction when someone does slashing damage to it.
The martial classes do not seem overly complex to me. More complex than the Champion Fighter, but about on par with the Battlemaster, Paladin, and Monk in 5th Edition. What is a lot more complex is the situations they will likely find themselves in. Every monster is written like a little puzzle to figure out. Things like weapon choice, movement and positioning, and dealing with powerful debuffs are going to be regular features of play.