the 145th King of the Fritz Family, which are Ymir's descendants, along with some other Eldians moved to Paradis Island, which is where the Wall was build. therefore the Wall people are Eldians. some Eldians stayed at the main land though and lost the war to the Marleys, because the 145th King Fritz abadoned them and the Marleys gained control of the Eldians there.
I wonder how did the Eldians at the mainland felt when they were left behind when the 145th King Fritz left and abandoned them. I wonder if there were memories from the past left behind by the previous titan shifters then to the ones who are holding it, i mean if there were memories or feelings such as hatred to the king hence progenitor titan who decided to abandon the leftover eldians at the mainland. Since you know the Eldians had no choice the first place and were left to die and conquered by the Marleys. Which is why they have no sense or feelings of humanity towards the people in the wall now.
So I'm finally understanding what's been happening but since I'm stupid and shit did the eldians give in to the Marley's and are the people inside the wall Marley's or eldians or are they not specified? Can someone answer my question(￣∇￣")