Correct, but there's more to it.
These are the textbook definitions of the Koine Greek word "
ἀδελφοί"
(adelphoi;brothers): "fellow-countryman," "disciple/follower," "one of the same faith," and "kinsman, or relative," etc.
The context of Matt. 13:55/Mk.6:3 shows the definition that applies to the word "
ἀδελφοί" is "
kinsman, or relative" in those verses. Now, what information shows us what
type of family members they were?
When I ask you to present evidence that shows siblings is the type of family members Jesus's brothers (kinsmen/relatives) Joseph, Simon, James, and Judas (Jude/Thaddeus) were to Him you don't give any. Instead, you just say "They're called brothers, and thus siblings." Without evidence to support that it's just an assumption.
I, however, have actually given
something (scriptural verses and early Christian testimonies), which is better than your
nothing, to show they were the sons of Jesus's uncle, and thus His cousins. Another thing you don't do is actually show why that evidence of mine doesn't show what I claim it does.