A couple of things here: #1 we do not know who exactly asked this question. Jesus was in the town synagogue teaching. It was his wise sayings and apparent miracles that brought about the question of His identity. I’m sure the town gossip was already primed.
This was not an ordinary man. why not? his wisdom and his mighty works tell us this.
It may be that Joseph was already dead for whatever reason,
I don’t think anyone knows. But Jesus’ home town was trying to piece together how this son of a carpenter had such wise sayings and miraculous works.
So they clearly started to examine Him and His immediate family, to which they obviously rejected once they understood all that was at stake. To say they were examining His distant relatives as proof to one’s common origin, is a stretch. It would make no sense to argue from the standpoint of immediate family if only His mother was immediate. It actually weakens the argument.
When the Greek counterpart for the word “brother” is employed, there is no drifting. The Greek word for cousin on the other hand is the word syngenes’ and it can also be translated, Kin, Kinsfolk, Kinsman. The Holman translation also uses the word relative.
But that is not the word employed in Matthew 13:55.
#2 If the holy Spirit wanted to convey this narrow truth, (that Mary had no other Children) and he wanted to secure it as a truth in every generation, He could have easily employed the Greek word syngenes’. Anyone in history is welcome to give their opinion including those you’ve mentioned. But none of them rise to the authority of holy scripture.
After naming Christ’ family members and realizing they were a common family, then they became “offended.” Why? He had to be all human but nothing more! After all His immediate family, the ones located at His home, are all with us.
But Jesus’ response is telling. “A prophet is not without honor except in his own country and in his own HOUSE.” Not even his immediate family believed in Him at this point, with the acception of Mary. This was the thrust of His point. The members of His own household (His personal home) did not believe He was the Christ. Only Jesus could say the things He was saying and do the things He was doing because He was God come in flesh. A truth the Jews all denied in this chapter.