Just to add a bit more to @nforme_7108 mentioned. Unclear and busy backgrounds often trigger Firefly from creating a video. You may want to take an image into PS, use generative fill, or remove the background. The clearer the subject is the more likely Firefly video is to work.
Adobe Firefly sometimes blocks image-to-video generation if it thinks the image violates safety guidelines even if it doesn't. This is a known bug that some users have reported, and it’s still unresolved. Until Adobe fixes it, the only workaround is slightly editing the image or generating a new one before trying again.
Thanks for reaching out. The image you are trying to upload has a child; Firefly will not use any image with a child. This is a known limitation. Please let us know if you require further assistance.