The very earliest power chords are credited to 1950’s bluesmen. Music historian Robert Palmer (not the same man as the 1980’s singer named Robert Palmer by the way) cites Willie Johnson (on Howlin’ Wolf’s “How Many More Years” that was recorded in 1951) and Pat Hare (on James Cotton’s “Cotton Crop Blues” that was recorded in 1954). If the name of the former song rings a bell, you are likely remembering “How Many More Times”, the last and longest track on Led Zeppelin’s 1969 debut album, Led Zeppelin. Under his real name, Chester Burnett, Howlin’ Wolf got a songwriting credit on later editions of the album. Anyway, the Brits liked what they heard and launched the British Invasion, and the rest is history.
Whether or not Link Wray heard these records and got the idea has not been established as far as I know.