Answer

There are indeed many stars in the galaxy, yet in a sense the galaxy is still very empty. If we imagine our sun through a basketball (say, with a diameter of 30cm) the closest star is a basketball 8700 km from that first ball.

You understand, if two basketballs are floating 8,700 km apart, there’s a lot of room left to see between those balls.

Mind you, this simple reasoning does not hold in all directions. The Milky Way is a flat disk in which, in addition to stars, there are also extensive dust clouds. If we look in the direction of the disk (which they themselves are also in), our view is indeed quickly limited by these clouds. Thus we cannot perceive the actual center of the galaxy. It’s completely hidden behind those clouds. Appendix 1 shows such an interstellar cloud in the constellation Aquila, so flat in the disk of the galaxy. It looks like a hole in the sky, but actually the cloud is closer than the stars in the photo and blocks the light from the stars behind it.

But if we look perpendicular to the disk, up or down to put it that way, we do have a sufficiently open view of the universe beyond our galaxy, and we see countless other galaxies.

The 2nd picture shows the Hubble ultra deep field, a shot in the constellation Ursa Maior (Perpendicular to the plane of the Milky Way). There are 10,000 extragalactic systems on the complete image.