Interesting, ubiquitin-I’ll take your challenge. 6 of the mitzvos on your list are ones we cannot do today either. (And according to chazal no one ever did the mitzva of Ben Soreh Umoreh, since it never happened, that makes 7) We also have no sanhedrin, no beis hamikdash, etc. Yet, the general statement that Jews keep the Mitzvos today is still valid.
The mitzva of maaser is attributed to Yitzchak Avinu, by the way.
Yehuda and sons did a type of yibum.
and what about “Im Lavan garti, vtaryag mitzvos shamarti”?
Even if we argue about the extent to which the avos kept the mitzvos, the fact that there is such an opinion with many chazals supporting it, indicates that we cannot take the “reasons” at face value.
The point is, it is not that we should not be exploring the reasons of the mitzvos as much as we can, but that we should not base our willingness to do them on these reasons. Naase Vnishma means that we do no matter what, then we can delve into understanding the mitzvosto enhance our observance.