The Airplane version of Wooden Ships was released 6 months after the CSN version, but they were both recorded in March of 1969.
Furthermore, Paul Kantner co-wrote the song with Crosby and Stills, and the narrative concept is really Paul’s. Lyrically, it has a politically edgy tone to it that CSN lacked until Young joined the trio. The “wooden ship” that the three were sailing on off the coast of Florida - when and where the song was written - belonged to Crosby.
Therefore the Airplane version is not a cover. It’s an original, and arguably THE original. The fact that it is in so many ways a Kantner song may go to why - at least imho - it is the decidedly superior version.
Kantner did not get authorship credit on the CSN version because of some record label or contract thing.