It seems that the nature of the heavenly body was a topic amongst the Corinthians. Paul settles it in 1 Cor 15:35-49 by stating that the resurrected body is as different from our body as the difference is between our bodies and that of birds. I think it is a logical extrapolation from this point to the idea of there being no age distinction. We will not resemble fetuses or zygotes or old men because we will be completely different.
Did Jesus' resurrected body resemble ours? Or did it differ from ours as much as do those of birds? The resurrected Jesus was mistaken for the gardener. The apostles also took Him to be an ordinary man until "their eyes were opened.
Yet Jesus was able to pass through a closed door. That is something He could not do before His resurrection.
True, Paul described the resurrection body as different from the mortal body as a wheat plant is different from a grain of wheat. But I don't think Paul was talking about the difference in appearance. Rather he was talking about the difference in quality.
I Corinthians 15
41 There is one glory of the sun, and another glory of the moon, and another glory of the stars; for star differs from star in glory.
42 So is it with the resurrection of the dead. What is sown is perishable, what is raised is imperishable.
43 It is sown in dishonor, it is raised in glory. It is sown in weakness, it is raised in power.
44 It is sown a physical body, it is raised a spiritual body. If there is a physical body, there is also a spiritual body.
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48 As was the man of dust, so are those who are of the dust; and as is the man of heaven, so are those who are of heaven.
49 Just as we have borne the image of the man of dust, we shall also bear the image of the man of heaven.
Jesus is the man from heaven. When He was resurrected, He had the same body (though changed in nature) that He had on earth. He showed His disciples His wounds, and said, "A spirit does not have flesh and bones as you see that I have." It was an immortal body, and a spiritual body, but yet a human body. Our resurrected bodies will be similar.