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.

saltwater between it and Asia

If the Panama Canal doesn’t count, neither does the Suez Canal, IMO.

Technically no, not when using the same argument.

Australia (country) has Timor Sea and Arafura Sea on the north, not an ocean. But New Guinea belongs to Australia (continent), so it doesn’t actually matter, both sides of the sea are the same continent. Unless we consider only the main landmass of each continent and ignore all islands.

Panama, with it’s canal, is entirely in North America too, so the canal doesn’t matter anyway.

Same thing applies to Africa and Eurasia, no?