What level of אמונה was נח missing that he was called מקטני אמנה, and what is meant by his entering the תיבה מפני מי המבול?

Posting this out of order because I heard it last night from an older Telzer Yid I gave a ride to.

The idea of אמונה as the sole motivator for what we do, without any הרכבה of other חשבונות is one which is certainly worth contemplating even not during that week’s פרשה.

מאמר ולעבדו בלבב שלם