One small moment of clarity.
Statistically it seems far more likely than not, if the facts as reported are correct:
1) That there would only have been around 20 Jameses dating from this time period with both father named Joseph and brother named Jesus, and:
2) That mentioning a brother's name on the ossuary is so rare (requiring a prominent brother) that only one other example of a mentioned brother has so far been found.
By many estimates, the permanent population of Jerusalem at that time was only around 50,000 -- quite a small place by today's standards.