Need an outsider's perspective

Greetings everyone, I've consulted multiple people whom I trust, and they gave me very conflicting opinions, so please bear with me and give me your honest opinion. Okay here it goes:

I work for a consulting firm, It's been 1.5 years now, this firm is such a big name and a lot of people are impressed when I bring it up, when I was accepted by them I was so joyous but man oh man was I wrong. From the very first week, it was obvious for me, there are a lot of problems with the manager and the employees there, the manager is:

1- Condesinding with the other employees but he is nice to me, which created a weird dynamic between me and them, they treat me okay but they are kinda envious of my relationship with him.

2- there are personal problems between one of the seniors and the manager, and non of them refuse to speak to the other, basically this senior roams off without any tasks whatsoever.

3- another senior is basically the CEO's cousin and he has absolutely no knowledge of the work and does nothing all day except bring us morning coffee, this guy is like a few years away from retirement.

4- Me and one other guy do the job of 4 people, the work load is insane, I have no social life because i'm trying to finish the work

5- my last performance evaluation wasn't fair cause the manager gave the older senior the highest evolution cause he is the oldest and he needs a push to work (he still doesn't work)

6- I am so emotionally exhausted cause after all the work I do I get zero credit, my managers a lot of the time makes me feel like my work is bad and isn't worth it and a lot of the time he overloads me cause I care

On the other hand I want you all keep in minds the following:

1- this job pays very well, I tried looking for another job and I barely found anything but the pay wasn't as good.

2- I live nearby so traffic isn't eating me alive

3- my manager is a nice person other than all the things I've mentioned he really is compassionate (I take vacations when I want he never says anything).

I of course tried explaining all this to him, he delegated some of my responsibilities to the other guy for a while but then things went back to what it was.

I am so frustrated cause he isn't changing anything even though he can, I've been fighting my demons for over a year and a half not to resign from this job cause it stresses me out, All the work currently is basically repetitive. And I have no التزامات that I have to pay, I saved some cash to support myself if I end up resigning till I find something else. I am a girl idk if that is relevant.

would you resign if you were in my place? espicially that it's becoming worse after 2 years