If I could first ask, what form or school of Buddhism is he into (there are quite a number of them)? Is he leaning into
%between%,
Mahayana, or even the esoteric
Vajrayana? Supposing that he’s into Mahayana, does he identify with Zen,
Nichiren Buddhism,
Pure Land,
Tiantai/Tendai or everything else in between? (Living in a country where the majority of people is at least nominally Buddhist, you can’t help but have a professional interest in these things

)
As for Śākyamuni, aka Siddhattha Gotama/Siddhārtha Gautama (there are many buddhas in Buddhism so I’ll call him by that to make things clearer), you are correct that at least in Theravada Buddhism, Śākyamuni was human, albeit endowed with the greatest psychic powers - that is, he is a sort of super-man, the supreme kind of man there is. Although the Theravada school does not emphasize the more supernatural and divine aspects of the Buddha that are available in the
Pali Canon, elements of the Buddha as the supreme person are found throughout it. The
Madhupindika Sutta relates
thus:
Then, not long after the Blessed One (=Gotama) had left, this thought occurred to the monks: “
This brief statement the Blessed One made, after which he went into his dwelling without analyzing the detailed meaning — i.e., ‘If, with regard to the cause whereby the perceptions & categories of complication assail a person, there is nothing to relish… that is where these evil, unskillful things cease without remainder’: now who might analyze the unanalyzed detailed meaning of this brief statement?” Then the thought occurred to them, “
Venerable Maha Kaccana is praised by the Teacher and esteemed by his knowledgeable companions in the holy life. He is capable of analyzing the unanalyzed detailed meaning of this brief statement. Suppose we were to go to him and, on arrival, question him about this matter.”
So the monks went to Venerable Maha Kaccana and, on arrival exchanged courteous greetings with him. After an exchange of friendly greetings & courtesies, they sat to one side. As they were sitting there, they [told him what had happened, and added,] “
Analyze the meaning, Venerable Maha Kaccana!”
[He replied:] “
Friends, it’s as if a man needing heartwood, looking for heartwood, wandering in search of heartwood — passing over the root & trunk of a standing tree possessing heartwood — were to imagine that heartwood should be sought among its branches & leaves. So it is with you, who — having bypassed the Blessed One when you were face to face with him, the Teacher — imagine that I should be asked about this matter. For knowing, the Blessed One knows; seeing, he sees. He is the Eye, he is Knowledge, he is Dhamma, he is Brahma. He is the speaker, the proclaimer, the elucidator of meaning, the giver of the Deathless, the lord of the Dhamma, the Tathagata. That was the time when you should have questioned him about this matter. However he answered, that was how you should have remembered it.”
“
Yes, friend Kaccana: knowing, the Blessed One knows; seeing, he sees. He is the Eye, he is Knowledge, he is Dhamma, he is Brahma. He is the speaker, the proclaimer, the elucidator of meaning, the giver of the Deathless, the lord of the Dhamma, the Tathagata. That was the time when we should have questioned him about this matter. However he answered, that was how we should have remembered it. But you are praised by the Teacher and esteemed by your knowledgeable companions in the holy life. You are capable of analyzing the unanalyzed detailed meaning of this brief statement. Analyze the meaning, Venerable Maha Kaccana!”
According to the Canon, he was
born as a human, albeit highly spiritually developed as a result of the previous lives in the career of the
bodhisatta. With his attaining the
bodhi (“awakening”; i.e. enlightenment), however, he perfected and transcended his human condition. When asked whether he was a
deva (the closest thing to ‘gods’ in Buddhism; cf. the Hindu
deva) or a human, he replied that he had eliminated the deep-rooted unconscious traits that would make him either one. He is a
buddha, one who had grown up in the world but had now gone beyond it, as a lotus grows from the water but blossoms above it, unsoiled. He is such that the Canon even names him as the “
teacher of the gods (devas)
and humans”, superior to both in the sense of having
nirvana or the greatest bliss, whereas both deva and man are still bound by desires, emotions and stuff like that (
kilesa).