Final answer:
Chordates are the taxa most closely related to humans, as both fall under the Deuterostomia superphylum due to their patterns of embryonic development. Echinoderms also belong to this superphylum but are less closely related than chordates.
Step-by-step explanation:
The taxa that share the most common ancestry with humans are Chordates. Within the various groupings of animals, the Chordates and Echinoderms fall into the superphylum known as Deuterostomia. This categorization is based on embryonic development patterns where echinoderms and chordates develop their mouths second, contrary to protostomes like mollusks and arthropods, where the mouth develops first. The phylum Chordata not only includes humans but also other vertebrates and some invertebrates. Despite some other invertebrates like mollusks, annelids, and arthropods showing clear distinctions, it is the deuterostomic development of echinoderms that reveals their closer relatedness to humans and other chordates.