A person is a person. Refer to the individual as such.
1)If anybody asked you about the money, tell the person that it is in my bank account.
2)I felt that somebody was in the garden but I did not see anyone.
3) Speaker 1: A friend of mine helped me a lot.
Speaker 2: You should thank that friend/buddy/comrade/confidant
4)Congratulations on your new baby! What's the baby's/ child's/ offspring's/ broodspawn's/ youngster's/ squirt's / toddler's/ tyke's/ kid's/ infant's/ youth's name?