I see two impostors, not one. Asia and Europe.

Africa is not seperated by ocean to Asia, and North/South America is also not separated by ocean…so really only Antarctica and Australia are not imposters.

If you count the Suez Canal and squint, you can make an argument. Not so much for the above.

The panama canal is not an ocean…and man made. No amount of squinting could make it a reasonable argument to count it.

Africa is not a continent either then?

Africa being an ocean is supported by there being saltwater between it and Asia. The panama canal(s) connect freshwater lakes to bridge the gap between the Pacific and the Atlantic.