The evolution of any specific organism is the product of historical coincidences, most dramatically in the aftermath of geophysical events which have provoked mass extinctions. This is a strong counterargument against the idea of evolution having an overarching trend. Another argument against evolutionary trending has been the continuing diversity of life in every phylum.
In hindsight, with details stripped out, history may be interpreted as directional movements. The mind’s propensity for patterns engenders this. But the breadth of life and vast diversity of circumstances which invoke adaptation defies characterizing evolution in the large.
We do not understand why the actual complexity realized in evolution is far less than what seems to be possible genetically. ~ Sean Carroll
Evolutionary theories typically suffer survivorship bias: the clades that last are those that theory relies upon. Short-lived clades are ignored or treated as oddities. History is written by the victors. Hence, patterns are perceived which do not aptly characterize evolution.
Though evolution does not have an overarching trend, it does exhibit patterns regarding inclinations, means, and constraints. Evolution exercises a little localized vector, but not a big one.