I don’t think He did, it only seems that way to our modern minds. All through Scripture, God spoke through and to people using terms they were familiar with. So, ancient prophets saw and wrote images familiar to ancient civilizations, Jesus used images familiar to people in a first-century agrarian society, Paul used popular Greek poets, etc. In all those cases, we have to dig into the ancient context to understand what is being said.
Similarly, when God gave the creation accounts, it appears He used styles and terms common to Bronze Age creation writings. People at that time, and probably especially someone raised in Pharaoh’s court, would have recognized it easily. Since at least the initial passages must be divine revelation, the technique is similar to the way visions in Revelation were given and written in a standard apocryphal literary style. Both seem obtuse to us and easy to misconstrue if we don’t take the effort understand the original context.
Now, this raises a slightly different question. If the initial passages are prophetic revelation of some sort, why didn’t God point that out, like in other prophecies? At least two possible reasons.
First, there are many things in Scripture that seem inscrutable and don’t necessarily follow clear patterns. In my opinion, one reason God may have done this is so that we don’t fall in the trap of depending on rules to understand spiritual truths, but rather depend on an active relationship with Him. In other words, when we encounter something challenging, perhaps He would have us seek understanding through, say, prayer and fasting, as much as hermeneutics and exegesis.
Second, Scripture clearly states that God uses figurative terms when speaking through prophets (Numbers 12:6-8, and although Moses is slightly different, there is a similar observation concerning what God spoke through him). However, I don’t know that Scripture ever clearly says that God will always state clearly that He is speaking this way. In fact, a number of passages in the Gospels show that Jesus made spiritual statements without any such preface, and clearly expected correct discernment from both His “unschooled” disciples (eg Matt. 15:10-16, Mark 8:13-21, John 6:51-53, etc), and educated Jews (John 3:4-10).
So my perspective on why the initial account seems so easily confused is because we are approaching it with the mindset and tools of modern Western thinking, rather than with a spiritual and ancient Biblical perspective. We attempt to read it with minds conditioned to see historical narrative as only a scientific style, and not a theological style.