As-salamu alaykum - struggling to understand slavery in Islamic history

As-salamu alaykum. I’ve been reading a lot of history lately about the Arab world, East Africa, and figures like Tippu Tip, and the more I learn the more uneasy and confused I feel. I believe slavery is completely inhumane and that we are only slaves to Allah, so discovering how slavery existed among Arabs and in early Muslim societies has been really upsetting to me. I even came across accounts that during some periods Muslims captured people from Europe, the Mediterranean, and the Caucasus, and that some enslaved women were forced into sexual servitude. Astaghfirullah - reading that made me very uncomfortable. I’m also confused about slavery in the time of the Prophet Muhammad (Sallallahu Alayhi Wasallam). I understand he didn’t immediately abolish slavery, and that there were people he owned, bought, and later freed. He stressed kindness toward those in servitude, encouraged manumission, and affirmed rights and dignity for them. Examples like Bilal, who was freed and became the muezzin, and Zayd, who remained part of the Prophet’s household even after being freed, stick in my mind. But I can’t see the whole picture. Did the Prophet’s actions mean slavery was sanctioned by Islam then, or was it treated as a temporary social reality meant to be phased out? How do scholars explain that he both had slaves and strongly promoted good treatment and freeing of people? I know slavery was widespread across many societies at the time, not just among Arabs, but I still wrestle with why it was present in early Muslim communities and why it wasn’t banned right away. I sincerely want to know what Islam taught about this and how Muslims should understand it now. This topic causes me real anxiety and I’m looking for clarity, not confrontation. I’d appreciate thoughtful, respectful explanations from people who know the history and the religion well. Jazakum Allahu khairan for any insight.