Supposedly, everything in God’s plan is about love. I have no way to reconcile that with what I am about to say, but perhaps God just wanted to create some beings embedded in time. How are time and love related? I really don’t know, but that’s my impression since that seems to be one of the crucial differences between ourselves and the angels.
Angels also live in time, inasmuch as they began existence at a point in time. They did not always exist.
However, the OP poses a very intriguing question; why are we enfleshed? What was God’s purpose in making us creatures of both body and soul? Why not just souls? We could be just souls and have free will.
But would we be like angels if we were just souls? Would we have united intellects and wills, as they do, so that a choice for good or evil, once made, would be irreversible? If matter is the “preventive factor” of such things as irrevocable decisionmaking, or even direct infusion of knowledge from God, then one might ask what is the point of imposing the limitations of matter on us?
We can’t know the Mind of God, of course, so we don’t really know why God wanted us to have bodies. But we can speculate, and it’s interesting to do it. Possibly God’s love is such that He wants to forgive transgressions. Once an angel has made a decision there’s no forgiveness involved because the angel’s decision is irrevocable. God does not forgive angels because the fallen ones won’t accept it. But we can, and we do. His love for fallen angels is always unrequited, but with us, we can accept it notwithstanding our having previously rejected it.
But let’s assume for a moment that a spiritual being can change its mind. Then why bodies? Well, quite possibly God loves matter. What we know about matter is severely limited. We don’t even know what was “there” before the Big Bang, and it appears we can’t know. We can’t trace anything back before it because it changed everything, or so the physicists tell us.
We can think, well, perhaps God loves the fact that from congealed energy in the form of cosmic dust, His plan was (among other things) for it to eventually form a juicy pear. And since angels don’t eat juicy pears and can’t directly and in a material way, enjoy a juicy pear, then perhaps God wanted a creature that could. Matter enjoying matter so artfully constructed that it would delight.
Angels, no doubt, can see the atomic structure of a pear and understand it intellectually in a way we never will. But that angel still can’t bite into it and experience it materially. We can.
And possibly, in the beginning, God made us so we would enjoy all things material as well as spiritual, and perhaps we did. But we chose (and still choose) to decide for ourselves. “I don’t like brussel’s sprouts and won’t eat them despite the fact that they’re good for me. I’m going to eat all of this sugar despite the fact that it may hasten my death. I’ll choose it anyway.” We do that.
Perhaps before the fall, we ate the brussells sprouts and found them admirable precisely because they were there and were edible and we knew directly that God meant for us to eat them. Perhaps we liked sugary pears better but ate the brussells sprouts anyway because it was part of God’s Providence that we would do so and be satisfied whether we were eating brussells sprouts or pears.
I think if we knew why God created matter at all, we might know why he made us composite creatures. But since we don’t know the first, we don’t know the second.
All we can do is guess at it.
(Oh yes. No offense to those who like brussels sprouts. I hate them myself, but do not claim that no one should. I just used them as an example.)
