I understand where you are coming from, but the child is still very very young and may struggle to communicate. I My son is 3 and has only started speaking since the start of lockdown. He started nursery at two and compared to the other children he was non verbal. It will be hard hearing it all the time, but imagine how the parents feel dealing with it. At 1.5 he will have huge tantrums as he cant understand the word no, regulate his emotions or have any understanding of things. You as an adult can use head phones or sound muffling ones. In this sense I do think you are being a bit unreasonable as if your listening to music to drown him out, then why not use headphone? . I used to appologise to my neighbores as i thought at times they would think i was murdering him. They all laughed, said they knew as they had kids themselves, and said not to worry.
However if my child was screaming due to his limited understanding and lack of verbal skills, and my neighbore above blared music out I would be annoyed as it just makes the situation worse.
I posted recently about getting back at my druggie neighbore playing baby shark and got told in no uncertain terms how selfish this would be to my other neighbores. They were right and i took that on board.
Maybe the best way to deal with it aside from headphones is to get friendly with the parents and find out a bit more about the situation. You do still have to live above them and as was explained to me, petry games even though you are at the end of your tether, doesnt actually solve anything other than making it worse for everyone.
I think a bit of compassion here could go a long way