What is manifestation?
Is every person a manifestation?
Manifestation of God according to Baha'i theology
Throughout the ages, humanity’s spiritual, intellectual and moral capacities have been cultivated by the Founders of the great religions, among them Abraham, Krishna, Zoroaster, Moses, Buddha, Jesus Christ, Muhammad, and—in more recent times—the Báb and Bahá’u’lláh.
These Figures are not simply ordinary people with a greater knowledge than others. Rather they are Manifestations of God, Who have exerted an incomparable influence on the evolution of human society. While each of Them has a distinct individuality and a definite mission, the Manifestations of God all share in a single, divinely-ordained purpose—to “educate the souls of men, and refine the character of every living man…”
Manifestations of God | What Bahá’ís Believe
Manifestation of God - Wikipedia
In short of what you described, Baha'i believes in the Trinity?
Baha'is believe in the Divinity of Christ, His Sonship, the Holy Spirit and the Father. We don't adhere to any doctrine of the Trinity, not do we recite any creed where the Trinity is mentioned.