No, the bible doesn't state 24-hour day.
No one here is claiming it was 24-hour day except you, so you have basically bludgeon this straw man to death.
But Genesis was very clear and explicit that one "creative day" is "evening and morning". So it does mean a day is equaled to light and darkness, or day and night:
The same pattern of "And there was evening and there was morning...the ____ day." is repeated 5 more day in Genesis 1.
What does that tell me, URAVVIP2ME?
I don't know how I can make any clearer to you. Sure, it does say hours, or 24-hour, but "there was evening and there was morning", is not unknown measure of time.
It tell me that a "day" in Genesis 1, is just that - a day - and that "day" comprises of "evening and morning".
What It doesn't say the "evening and morning" is made of one year, one decade, one century or one millennium.
What is written in 2 Peter 3:8, about "one day is like a thousand years, and a thousand years are like one day", which SOME Christians used to interpret Genesis 1, is nothing but apologetic BS. This verse by Peter has nothing to do with Genesis 1.
The correct way to interpret Peter's verse (3:8), is that one day and one thousand years have no meaning to this Lord, but it say nothing about creation. The theme about 1 Peter 3, and I am talking about the whole chapter, is that God is willing to wait for any amount of time for you to repent of your sin, whether that be 1 day from now, or 1000 years. It had nothing to do with Genesis 1.
Genesis 1 is very specific about each day, is nothing more than just one "evening and morning".
So your claim that it is "but literal unknown length-of-time days.", is BS, because it does say "evening and morning" in verses 1:5, 1:8, 1:13, 1:19 1:23 & 1:31. To say that "evening and morning" is "unknown" measure of time, only just show the absurdity of your dishonesty.
One of the reason why I didn't convert and become Christians, is people like you, trying to twist words around, to make the bible say what you believe it say, taking verses out of context. That's the sort of dishonesty, I wouldn't want to be associated with.
The chapter (Genesis 1) may not specify 24 hours, but it is very specific with the time frame for each day: "And there was evening and there was morning..."
2 Peter 3 was written from different time with different theme to Genesis 1, so you can't really them together, as if they are related when they are not.
Genesis chapter one is about getting the earth ready for mankind to inhabit earth.
No, I am Not claiming a 24-hour creative day. Each creative day can be of the same of differing time lengths.
Just as your grandfather's day can be different in time length from Noah's day. Yet both are referred to as ' day '
What does Genesis 2:4 say about all of the creative days?
Doesn't it say ' in the day ' (singular ) that God made earth and heaven?
What does Genesis 1:5 say ? God called the light ' day ' and the darkness He called ' night'
So, yes, daylight hours can properly be called ' day ' but that does Not mean the 24-hour day is Not 24-hours long.
An ' evening and morning ' does Not mean each creative day was 12 hours long.
So, the word ' day' in Scripture has shades of meaning.
We are nearing the threshold of Matthew 25 vs 31,32 the ' time of separation ' when Jesus will involve himself into mankind's affairs and wicked people will have No more length of time to repent but be cut off from all life and be destroyed forever - Psalm 92:7