I think everything really does happen at once.
For example, I've been resurrecting some of my old writings from 38-41 years ago, and it occurs to me how valuable it is to have saved these things. Because they are a part of me. Not they "were" a part of me; they are a part of me. They are part of me that is becoming who I am today.
It is hard to conceive of time as an illusion, yet it is just one part of the time-space continuum. Time is an illusion in which we believe, just as we believe in the color red because it excites certain receptors in our brain. There is no objective reality of the human experience of "red." You can't describe it to a blind person. Butterflies see ultra-violet colors and dogs hear higher-pitched sounds and live in a rich world of smells that would be completely unintelligible to us. If we had the right receptors and the right neural networks, we could perceive those worlds, too.
Other forms of existence must perceive time much differently than we do, if indeed there is such a perception beyond humans. A tree would sense the passage of time very differently than we do. Think about it.
So this is what I mean by saying that the "me" that was around in 1965 and wrote those words is part of the "me" that is sitting in my chair at home typing this.
I'm talking about evolution. Individual evolution. We evolve through the passage of time, and we continue this journey as long as we live. After that, we continue our journey, but the form of our consciousness changes, and we sift back into the larger universe of which have always been a part.
Time is a cylinder of space that we occupy on our journey through life. We occupy all parts of our life at once, but we are unable to perceive the earlier parts without leaving some trace behind, like the children in the fairy story who left a trail of bread crumbs with which to find their way back home. For most people the traces of their memory are enough.
I must write. I've always needed to write stuff down, because my consciousness is too easily distracted to remember much. It seems to me that the breadth of my experience is so large that I can barely take it all in at once at the time I am experiencing it, let alone correctly retain or recall the memory of that experience from an earlier time. The additional perspectives I can gain through my writings allow me to more thoroughly understand who I am. It is through this means that I can puncture my personal illusion of time and begin to embrace my entire being.
I have always been curious about things like this.