Even once you understand that the uncertainty principle is not the same as the observer effect, I think it’s still mysterious for the same reason that “the wavefunction is the only thing that exists” is mysterious.
If anything, it’s more mysterious once you understand the difference. People are more willing to accept “Your height cannot be measured with infinite precision” than “Your height fundamentally has no definite value”, but the latter is closer to the truth than the former.
Even once you understand that the uncertainty principle is not the same as the observer effect, I think it’s still mysterious for the same reason that “the wavefunction is the only thing that exists” is mysterious.
If anything, it’s more mysterious once you understand the difference. People are more willing to accept “Your height cannot be measured with infinite precision” than “Your height fundamentally has no definite value”, but the latter is closer to the truth than the former.