We're 3+1 dimensional beings. Time doesn't have the same metric as spacial dimensions, so you can't add them together. You can't rotate a temporal object along

We're 3+1 dimensional beings. Time doesn't have the same metric as spacial dimensions, so you can't add them together. You can't rotate a temporal object along the xt-plane, for example, nor can you speak about an object's length along the t-axis. The three spacial dimensions are interchangeable, but time is special, so calling it 4D is incorrect.