Absolutely. No question its a 24 hour period. I don’t know how God could make it any clearer.
Genesis 1:5 (KJV)
5 And God called the light Day, and the darkness he called Night. And the evening and the morning were the first day.
Genesis 1:8 (KJV)
8 And God called the firmament Heaven. And the evening and the morning were the second day.
Genesis 1:13 (KJV) All plant life created here.
13 And the evening and the morning were the third day.
Genesis 1:19 (KJV) Sun created here.
19 And the evening and the morning were the fourth day.
Genesis 1:23 (KJV)
23 And the evening and the morning were the fifth day.
Genesis 1:31 (KJV)
31 And God saw every thing that he had made, and, behold, it was very good. And the evening and the morning were the sixth day.
A better question to consider is what took place between Genesis 1:1 and 1:2? Why did the Earth BECOME formless, empty, covered in water - all forms of judgment.
Well - it would have been more clear if He hadn't created the sun after he called the first day and the first night. Or created plants before he created the sun. Of course there may have been another source of light energy that the plants used and it was replaced by the sun. (Just as rain fell for the first time during the flood, and replaced the daily fog/mist that previously had watered the plants.)
I do believe in the Creation story.
I also believe in the idea of a “day” means a period of time.
I also believe that the ancients were trying to describe the greater truths and the idea of God in the best way that they could. And obviously today, it is impossible for us to completely understand God.
Personally, I think there is something to do with the “Big Bang” on the first day. That is when God created energy - “And God said let there be light”. And from that light energy (and E=MC2), everything else was thus created for God to form as He wished.