There's where things are fuzzy, at least to me. Quoting directly from the source material:

"You can use a bonus action to magically manifest an echo of yourself in an unoccupied space you can see within 15 feet of you. This echo is a magical, translucent, gray image of you that lasts until it is destroyed, until you dismiss it as a bonus action, until you manifest another echo, or until you’re incapacitated.

Your echo has AC 14 + your proficiency bonus, 1 hit point, and immunity to all conditions. If it has to make a saving throw, it uses your saving throw bonus for the roll. It is the same size as you, and it occupies its space. On your turn, you can mentally command the echo to move up to 30 feet in any direction (no action required). If your echo is ever more than 30 feet from you at the end of your turn, it is destroyed."

It doesn't specifically say that it is a creature. It has its own AC, HP, Resistances/Immunities, Occupies a space, and can make saving throws, all qualities you would find in a creature and not an illusion. The point where I feel I am getting confused is that the echo is supposed to be a copy/image of you, making this fall into some weird gray area. Everything is pointing to it being treated as one.