Although we base our religious lives on the Scriptures, we at times find them hard to follow. That is true of today's first reading, and the Gospel.
The first reading tells how word of the death of Saul had come to David, he and his wives wept bitterly for their fallen rulers.
As for the Gospel, it followed on years of David quietly aiding Joseph in his carpenter work. With no other accounts of Jesus growing up with his relatives, we cannot understand how they deemed him lacking when he came out of his quiet years.