Romans 8 is about benefits to those in Christ, not an exclusive statement limiting the atonement's extent

The structure of Romans 1-8 is: all are lost in sin (ch. 1-3), justified by faith (ch. 4-5), dead to sin in Christ (ch. 6-7), benefits of being in Christ (ch. 8). The passage addresses those who ARE in Christ and their benefits — not a statement that Jesus only died for those people. The "us" is the community of the believing, not an exhaustive list of everyone Christ died for.