Hardly. This type of arrangement was short-lived and anomalous. It was roughly true in rich economies during a few decades of the post-war era. Never before, and not for most people around the world.

Relationships are worth cultivating any time, of course, but one shouldn't mistake a job for a life. The idea that a job is for life and your employer is your family was a mind hack that worked for a short while and is now unraveling.

Just looking at the Western world that breaks down during industrialization and falls apart if you go further back then that, journeymen (i.e. tradesmen who had completed their apprenticeship) would often literally travel from town to town for several years to work under different masters before submitting their work to a guild for evaluation and becoming masters themselves. I guess you could say serfs worked "for the same employer" because their feudal lords owned them as part of the territory but that seems like a stretch.

It's not so much that employees used to "keep working for the same employer for their entire lives", it's more that the people running and operating businesses used to be part of a local community and there used to be an understanding of a shared responsibility beyond private property claims.

This isn't something employees can change, either. Even employers aren't really able to change this because they too have to operate in the same economic system that contributes to this effect. It's probably more extreme in the US (and some places in the US more than others) but the economic system does not care for such sentimentalities and a business that does will put itself at an economic disadvantage, especially where the social fabric has already been sufficiently eroded to avoid bad optics (e.g. WalMart arguably failed in Germany because its attitude to employees felt extremely off-putting both to workers and consumers at the time but that resistance may have been eroded by the behavior of other companies since to the point where it would no longer make them stand out the same way if they tried to re-enter the market now - economic changes making this unfeasible notwithstanding).

"For entirety" definitely not. What you describe was a thing in some periods, typically periods where some group got too much power and they tended to end with huge disfunctions and breakdowns.

This is... not true. It's so not true I don't even know where to start rebutting it. But for a start, most of human history you were either hunting and gathering for yourself, keeping a flock for yourself, or farming land for yourself. "Employment" even as a concept is a pretty new concept on the scale of human history.