The First Creation could not exist without God. In this sense, God is necessary for First Creation. First Creation could not exist if God did not create it and help maintain it.
However, the First Creation is not a product of nothing. The Beings that inhabit the First Creation existed in some form before the First Creation. God is necessary for their existence as Beings in the First Creation, but God is not necessary for their existence before the First Creation.
In this sense, God is entirely, fundamentally unnecessary in the strict, core denotion of the word. The Beings that comprise the First Creation would have gone on existing in whatever form or mode they existed without God's intervention.
The pre-First Creation mode of existence was obviously deficient/lacking; thus, God's First Creation is a positive development. However, it is misleading to say that this positive development was absolutely necessary.
The same applies to Jesus and his Second Creation. Although Jesus is necessary for the creation of Heaven, it would be wrong to claim that following Jesus into Heaven is absolutely necessary.