All animal life achieves centrally organised awareness. Each species specialises during evolution in some way to perceive better its environment. Birds excel at vision and dogs at smell. The vulture manages both. Humans turned inwards to achieve self-awareness. Zoltan Torey (link here) explains its linkage to language, that other unique human ability. The capacity for language requires critical timing of child development, which synchronises the genetically controlled growth of the big brain with the group-inspired instillation of language during infancy. We can study infancy at first hand, but the contribution of the group has origins for too ancient for us to know. Our ignorance explains why we do not care to acknowledge how much it controls the minds of its members. The consensual agreements and concerted thought of the group that rears us directs us.
Not that we have good reason for blindness. Ancient lore accurately defines regular cycles of concerted human herd action. The saeculum, known since Etruscan times, governs group activity in regularly recurrent cycles, each of which have roughly the duration of a long human life. Strauss and Howe provide a masterly historical review. During four turnings of roughly a generation each, the cycle re-orients the values of the community from one extreme to its opposite and back again (see The Values Cycle). It exerts a social influence on group thought, regularly opening minds to change. Unfortunately, its stereotyped form culminates in major political, financial and combative crises, the turmoil of which have shaped civilisation. The study of saecular history gives a unique insight into present times (see their blog).
We need to realise that our thoughts, which feel so private and individual, resonate together in a communal hot tub, the group mind. The very thought offends my sense of person, and probably yours too, but it should not surprise you or me. The group gives us the ultimate gift of humanity, ideas. Language could only arise, survive and adapt in the medium of the group. Humans have more, not less, thralldom than the rest of the animal kingdom to the group. Sheep do not have obligatory herd mentality alone, but sheep do not threaten the world following their leaders. Self-aware thinking humans do, responding as a group to demagogues, who so monstrously tap prejudice, or to financiers, who exploit self-interest, or to politicians and clerics, who manipulate our beliefs. How can mere individuals redirect an errant group mind? I suggest starting to learn how it works.