Why does the Hebrew canon teach that a widow should marry her deceased...

[bat.andrea]

...husband's brother...? ... and name their first son after the deceased husband?

I read one explanation:
The reason a widow is expected to marry her deceased husband’s brother and name their first son after the deceased husband is that the soul of the deceased transmigrates (reincarnates) into the son the widow has with his brother.

... but I am interested in hearing other explanations for it -- from Orthodox Judaism, Reform Judaism, Conservative Judaism, Christianity, Islam...
I ask for Christian and Islamic explanations because they are also "People of the Book," abiding by their respective interpretations of the Hebrew canon... thus their insight would be valuable in that regard... as a point of comparison. The explanation I provided is Chasidic and is obviously very different than the other sects of Judaism. I want to have all the accepted interpretations in front of me before I pin down which one I agree with.