Just a quick note on what makes Premillennialism what it is. Premillennialism asserts there will be a future, earthly kingdom of the Messiah (Jesus) for a period of 1000 years.
There are four elements associated with Premillennialism: (1) a future kingdom; (2) an earthly kingdom; (3) a kingdom of the Messiah and (4) a kingdom that lasts for 1000 years.
I believe the first three elements are discussed in Scripture even before one looks at Revelation 20 and its mention of a 1000-year reign of Jesus and the saints.
First, that the kingdom is future is taught in passages like Matthew 6:10; 19:28; Luke 22:28-30; Acts 1:6; 2 Timothy 4:1; 2 Peter 1:11; Revelation 2:26-27; 19:15, etc.
Second, that the kingdom will be an earthly kingdom is taught in passages like Psalm 2; Psalm 72; Psalm 110; Isaiah 2:2-4; Isaiah 11; Zechariah 14:9; Matthew 5:5; 6:10; 19:28-30; 25:31; Rev. 5:10; 19:15, etc.
Third, that the kingdom is Messiah’s kingdom is taught in passages like Psalm 2; Psalm 110; Isaiah 9, 11; Luke 1:32-33; Acts 1:6, and many other texts, etc.
And then, fourth, Jesus’ kingdom is stated to last 1000 years before the Eternal State according to Revelation 20.
Note that the first three elements of Premillennialism mentioned above—(1) future, (2) earthly, and (3) Messiah’s kingdom—are well established in Scripture even before one looks at Revelation 20.
What is new in Revelation 20 is the fourth element—that Messiah’s kingdom will last 1000 years before the Eternal State of Revelation 21–22 begins.
Hypothetically, if we did not have Revelation 20, we could still know that there would be a future, earthly, kingdom of the Messiah from other Scripture texts. What we would not know is how long Messiah’s kingdom would be before the Eternal State.
So Revelation 20 contributes to the Premillennial understanding but it is not everything there is to the premillennial view.