There is great love for autumn. What makes this point even starker is that the first stanza is addressed to a different season, summer. Keats is saying that summer is beautiful, as things mature and grow. The language is one of undoubted admiration.
Season of mists and mellow fruitfulness,
Close bosom-friend of the maturing sun;
Conspiring with him how to load and bless
With fruit the vines that round the thatch-eves run;
The same goes for the season of spring, which is briefly mentioned in the last stanza in a rhetorical question - "Where are the songs of spring?"
But as we move along in the ode, Keats begins to enter into his main topic, the beauty of autumn. As he does this, the contrast becomes clearer. Autumn is as great as the other seasons, if not greater. In other words, summer and spring have their glories, but what is more glorious is autumn. Praise by way of contrast is one of the ways Keats shows admiration.
So, what is autumn like? It is a carefree and soft woman (stanza 2). Autumn has its own music, and nature joins that chorus to sing with lambs, crickets, and birds (stanza 3). All of this praises autumn. Therefore, autumn has no reason for insecurity.