It sounds like you may have been reading some rather lurid - and ideologically suspect - portrayals of indentured service, a system usually of signing your labour (not your person) over for a fixed term of years (often seven) at the end of which you were free to make your own way in the world with your new skills and a pay-off. Even this wasn't the lot of most workers and was itself far from a loss of all personal rights. The division between who had enforceable rights and those at the mercy of brutal owners wasn't between rich and poor, it was between free and unfree - i.e. slaves, the millions shipped in chains from Africa to toil in New World plantations and denied any rights whatsoever.

For the rest, life was hard for most, with average real incomes perhaps a twentieth of today's, but not so bad as you suggest: even the free poor had rights, though then as now offences might go unpunished, especially where the perpetrator was wealthy. Rape was an offence, beating of indentured servants and apprentices permitted but within limits. Otherwise, free wage labour (mostly agricultural in 1600, later increasingly industrial and urban) was the norm, or small semi-independent craft production which might similarly leave you at the mercy of what the local merchant was willing to pay for your goods.

Laws for the relief of the poor provided a rudimentary safety net in case of destitution. Of particular dread for all on low incomes (which meant most) were high food prices, usually following a poor harvest, at which times hunger was widespread though famine became scarcer after the 17th century: food riots were not uncommon. Far from being a brutalised, cowed mass, workers engaged in the political conflicts of the age, becoming enough of a menace in their own right to be banned from forming unions in both Britain and Revolutionary (!) France in the 1790s.

Except for slaves whose status was for life and hereditary unless freed by a personal act of manumission, social mobility always existed to some extent, though then as now it was limited (there's no point being a class if anyone can just saunter in and demand equal rank). And for everyone who moves up, someone may have to come down. One mechanism was inheritance, which in Britain favoured the eldest son, leaving the rest to make their own fortune or an advantageous marriage. The big losers were the rural smallholders and artisans who in the late 18th and early 19th century faced the impact of large-scale farming and factory industry, though others like Lancashire farmer Robert Peele who moved into the cloth trade in the 1630s might found a manufacturing dynasty whose heir with his followers would two centuries later pull of the not inconsiderable feat of founding both the modern Conservative and Liberal parties.