Macbook Pro Early 2015 won´t update from El capitan

Hi,

I never had Macbook before and just bought used Macbook Pro Early 2015 (i5 2,7, 8GB 1867 MHz DDR3, 128GB SSD) in which previous owner had Windows 10 installed. I reinstalled Mac OS from internet and got offered 10.11.6 El Capitan, so I installed this one hoping, it will update further once set up, but I don´t have option to update it from App Store - No updates available.

I tried google the answers, I found out, I´m not the only one with this issue, but I didn´t find solution, which would help me. I tried restarting Mac, restarting NVRAM/PRAM, trying to boot in safe mode, tried reinstalling from Recovery - but there is still only El Capitan, tried downloading new one from support.apple, but It´s not showing me any major OS after El Capitan, I can find only updates/patches.

Otherwise Macbook works fine, only issue is, there is broken screen, so I have to use external monitor, but that´s not an issue for me, could it somehow be problem for MBP to update? I should be able to update up to Monterey (I think). This is basically fresh installation, so I don´t need backup.

I know it´s older system, I know it´s not powerhouse, I just bought it for fun and trying different OS.

Im not really tech savvy in Mac world, so I would appreciate if your advices will be a little bit broadly explained.

Thanks in advance