This is one of the universal words in the Bantu languages although said slightly different
mtu = Swahili umuntu = Zulu, Ndebele munthu = Ndau, Chichewa munhu = Shona, umntu = Xhosa, motho = Sesotho,
I hope that helps. source: I am a Bantu native speaker
i just learned that MTU also means " someone" ( wikipedia) as a synonyme for " a person" why isn't it accepted ?
In a previous exercise someone explained that "tu" is a subject affix for "we". Is the plural invalidated by the "m" which indicates singular, or is "tu" only "we" when used as a prefix to verbs?
What you learnt is correct. However "mtu" is one full word which means "one person" or "a person" You cannot break the word into m- and -tu but we know that when it is singular it is mtu and when plural it becomes watu. Do not confuse this with the "tu" in tutaonana , which implies "we". I hope this helps.