Imagine that the universe is much older then 14 billion years. Our solar system may be older than 4.5 billion years. 

It is probable that the sun has formed and exploded several times since it first condensed.

The first time it formed from mainly gasses (hydrgen or simply ions) which were distributed throughout the universe.

In previous iterations, as it burned, it created heavier elememnts. Then at some point it exploded, throwing those heavier elements out into space.  But since there was a gravity well, the matter did not fly away to distant solar systems. It simply expanded and then collapsed to form a new sun and planets around it. 

In its current iteration, as the planets aged, some, like Mars, lost its solar wind protection, and the gasses and vapars in its atmosphere simply blew away. These gasses were blown until the force of the solar wind was overcome by gravity. This would be where the keiper belt is now. In the keiper belt these gasses and vapors condensed to form the many keiper belt objects. 

Most matter in our solar system was made here by our sun. The matter did NOT come from distant solar system where another sun exploded. The matter came from previous explosions of our own sun. 

IF the matter came from other solar systems, then the space between solar systems would still be full of ejecta from those events. It is NOT.

But we see formations occuring elsewhere from ejecta. Why would our area also not still be full of ejecta which is spewing from the many stars that explode thoughout the universe. Because like here, the matter expands until it is pulled back into the stars gravity well. A star that has exploded still has the same gravity as before it exploded. 

Some explosions are of blackholes. a blackhole can explode if it encounters another blackhole. the colision will cause an area where the event horizon is broken. Mass ejects from the broken event horizon. 

A black hole that is formed from a collapsed star explodes to make a normal nebula. a black hole that contains a complete galaxy will explode to form a diffuse nebula where new stars are formed.