(The only goal of all humanity is that of all species - spread genes.)
As a species yes, but is that all "humanity" is? If it were, we would have evolved to create food and fuck. At this stage, we have the food, but the fucking is decreasing rapidly.
Well-being means totally different things to different cultures.
In detail yes, but at the core? I don't think so. The idealistic view might suggest it, but the practical view of individuals are unlikely to back that up.
The less real diversity, the easier it is to convince them of buying, keeping the machine alive
And what we have done globally is condition homogenisation of thought and habit. The global cultural overlap is growing, as we all start to resemble the marketing plan.
As a whole? Yes, we're primarily bodies, animals. That's what we all have in common, all together. And that's where it stops. Everything that comes after, all the values and such, are splintered among the cultures as we all weigh them differently. I just don't think it's enough to be able to conclude that "Humanity as a whole strives for well-being." Yet. As you write, cultures are overlapping more and more, which is a shame. There are positives to it, but in my ideal world, we would have many cultures that get along with each other. But that's an utopia.