Here's Rabbi Samson Raphael Hirsch, as quoted by Rabbi Yitzchak Adlerstein:
Here is the basic sequence. Forgetting the special relationship between G-d and Man, (אנוש) even while retaining belief in Him, must lead to dissatisfaction with religious life. This leads in a following generation to an excessive preoccupation with material things simply for the sake of possession (קינן). Finding this vacuous and devoid of meaning, the next generation tries again to connect with G-d by asserting His existence and honoring Him with pious proclamations (מהללאל). Alas, the service of G-d through praise of the lips without subordinating one’s life to His dictates is bound to fail, so the next generation declines (ירד) once more. Detecting the stumbling, some look to educating a new generation (חנוך), ennobling them with something more meaningful. Such intensive education, however, remains the province of only a minority. The next generation is therefore one of “giving up the masses,” מתושלח.