More data for you to throw into the mix. It has to do with the washing of feet.
The ancient Jews considered the feet to be the filthiest part of the body (probably excluding elimination). The only other thing dirtier were the shoes that protected them. We can't remove our feet. But we can remove shoes. So, it was better to take one's shoes off and go through the house barefoot.
When barefooted from a long trip, the washing of feet was done only by slaves or the lowest servants. So, Jesus' washing the apostles' feet was a sign of Him "descending below all things."
And after one is baptized, washing of the feet as an ordinance make one "clean every whit." This was not a replacement for baptism. It was in addition to baptism. And even so, one had to be worthy. Even after Jesus washed Judas's feet, He said that "not all" are clean.
It is obviously not a "saving ordinance" since we are not all "required" to participate. But it is a reminder that even if we have been baptized, we still need to take care of those parts of our lives that bring us the greatest spiritual stain.
When Moses "came to the House of the Lord" (the mountain of the Lord's House) he needed to be clean every whit. This was part of the ordinance performed at the Burning Bush. So, he took of his shoes and his feet were washed. But I believe the Bush was also a means of cleansing with fire rather than water.