Psalm 115:16 is instructive for understanding what the biblical authors mean when they speak about “the heavens,” especially when they speak about “heaven” and “spiritual” together.

The heavens are Yahweh’s heavens,

And the land he has given to humanity. (Psalm 115:16)

The psalmist views heaven and earth as two realms. The realm above — the skies, השׁמים, ὁ οὐρανός — is Yahweh’s realm; the earth is ours. This worldview should inform how we read statements like this in the New Testament:

Blessed is the God and Father of our Lord Jesus Christ, the one who blessed us with every spiritual blessing in the heavenly places in Christ. (Ephesians 1:3)

Paul is saying that every blessing of God (of the Spirit, spiritual) and all that belongs to his realm (heavenly places) are ours in Christ.

You could combine the thought of both verses above like this:

The heavens are Yahweh’s heavens,

And the land he has given to humanity.

But in Christ, through the Spirit, all the blessings of God’s realm are ours. (Psalm 115:16 + Ephesians 1:3b)