The obliquity is approximately 23°27' but it is not fixed. Instead, it varies slowly because both the Earth's axis of rotation and its orbital motion are affected by the gravitational attractions of the Moon and planets. Our logo below shows what the obliquity looks like. The horizontal is the Earth's orbit, whilst the "pie wedge" shows the tilt of the equator. The line running through the globe is the axis of rotation, through the North and South Poles.
Over very long timescales (tens of thousands of years), the obliquity can be as small as 22° and as large as 24.5°.
Every day would be the same as every other. There would be no seasons. The whole world's weather would be completely different. Life would probably have evolved in a totally different way.
This is how Milton expressed it in Paradise Lost:
Some say, he bid the angels turn askance
The poles of earth twice ten degrees or more
From the sun's axle; they with labour push'd
Oblique the centric globe: some say, the sun
Was bid turn reins from th'equinoctial road
Like distant breadth to Taurus with the seven
Atlantic Sisters, and the Spartan Twins,
Up to the Tropic Crab; thence down amain
By Leo, and the Virgin, and the Scales
As deep as Capricorn, to bring in change
Of seasons to each clime.