I’ve been in a number of science ethics discussions and one prevailing idea was that the atomic bombs were “shiny new toys” and there were people pushing to use them at the expense of any other alternatives. (Obviously less flippantly than that.) This, of course, doesn’t make scientists look very good. So that’s what seems to make the narrative of saving more lives by dropping the bombs instead of a land invasion seem more palatable. Were there any alternatives being pursued? If so, what were they?
Not to dissuade other answers, but this particular question has been asked and answered quite a number of times by /u/restricteddata:
The tl;dr is that the US plan had always been to drop the bombs and invade.
There was an alternative, as Truman's "committee of three" (Grew, Stimson and Forrestal" recommended on July 2 in paragraph 12 of their proposed surrender ultimatum:
The occupying forces of the Allies shall be withdrawn from Japan as soon as our objectives are accomplished and there has been established, beyond doubt a peacefully inclined, responsible government of a character representative of the Japanese people. This may include a constitutional monarchy under the present dynasty if it be shown to the complete satisfaction of the world that such a government will never again aspire to aggression.
The advisors realised that some indication of the throne's survival was of crucial importance to the acceptability of surrender. But it seems to have been secretary of state Byrnes who prevailed upon Truman to leave out the reference to the monarchy as they journeyed to the Potsdam conference. Article 12 of the July 26 ultimatum retained requirement of a the peaceful representative government, but omitted all reference to the throne, the one thing that Hirohito and his advisers agreed must be preserved as they discussed surrender even after the bombings.
Even after the second bombing, Japanese top-level deliberations remained focused on protecting the throne. The August 10 Imperial Conference cabled Allied governments that
The Japanese Government are ready to accept the terms enumerated in the joint declaration which was issued at Potsdam on July 26th, 1945, by the heads of the Governments of the United States, Great Britain, and China, and later subscribed to by the Soviet Government, with the understanding that the said declaration does not comprise any demand which prejudices the prerogatives of His Majesty as a Sovereign Ruler.
Byrnes remained opposed to any explicit modification of "unconditional surrender", let alone one that would preserve the Emperor's constitutional powers contrary to both the Potsdam terms and the earlier draft. It was Navy Secretary Forrestal who broke the deadlock by proposing a more oblique form of words. Byrnes's reply of August 11 (received in Tokyo on the 12th) included the key provisions:
From the moment of surrender the authority of the Emperor and the Japanese Government to rule the state shall be subject to the Supreme Commander of the Allied powers who will take such steps as he deems proper to effectuate the surrender terms. The ultimate form of government of Japan shall, in accordance with the Potsdam Declaration, be established by the freely expressed will of the Japanese people.
"The authority of the Emperor... shall be subject" gave Hirohito just enough to overrule his military hawks and announce his decision to accept the clarified terms at the August 14 Imperial Conference. The bombings didn't bring surrender, the August 11 clarification did. That might have been done weeks earlier had the original terms been delivered: there's no way of knowing if it would have ended the war earlier, but the option of exploring the possibility existed.