There were some forms of slaves getting their freedom individually though
Certainly, but I don't think these played nearly as much of a role as class struggle and legal abolishment of slavery, even if the condition of recently freed slaves was on average hardly better than while they were slaves. In the US especially, they were still barred from owning property and were more or less forced into indentured servitude or similar relationships.
I admit, I don't have much knowledge on specific circumstances of slaves in colonies other than the US. The US did have lots of white indentures servants, but they were still treated better than black slaves or even free black people. Even with their contradictory talk of liberty while holding slaves, the laws the US enacted in fear of slave uprisings sometimes ended up limiting what the slave owners themselves could do with their slaves. Not only were free black people prevented from organizing in all ways - even talking on the street among free black people was dangerous at times, education of black people, slave or free, was forbidden because it was seen as dangerous - even when slave owners wanted to educate their slaves, they couldn't. Other laws also affected slave owners limiting what they could do with their slaves and enforcing certain things as mandatory, especially when it came to harsh punishments. Laws forbidding race mixing also prevented slave owners from recognizing any children they had with slaves which they might've wanted to recognize and limits were placed on individual slave owners from freeing their slaves. In their panic and fear of slave uprisings, the "liberty loving" slave owners created a society where even their own freedoms were limited.
This article also provides an eye-opening view into the various financial practices used by western capitalists to exploit entire countries.